Product details


Input voltage (type) DC/DC Topology Boost, Current Mode Vin (Min) (V) 2.5 Vin (Max) (V) 5.5 Iout (Max) (A) 1.5 Iq (Typ) (mA) 0.3 Features I2C Control, IR Mode Operating temperature range (C) -40 to 85 Dimming method Analog, PWM open-in-new Find other Illumination LED drivers

Package | Pins | Size

DSBGA (YFF) 12 2 mm² 1.32 x 1.7 open-in-new Find other Illumination LED drivers


  • 1.5 A Total Allowed LED Current During Operation
    (ILED1 + ILED2 = 1.5 A)
  • Dual Independent LED Current Source Programmability
  • Accurate and Programmable LED Current Range from
    1.4 mA to 1.5 A
  • Optimized Flash LED Current During Low Battery
    Conditions (IVFM)
  • > 85% Efficiency in Torch Mode (@ 100 mA) and
    Flash Mode (@1 A to 1.5 A)
  • Grounded Cathode LED Operation for Improved Thermal
  • Small Solution Size: < 16 mm2
  • Hardware Strobe Enable (STROBE)
  • Synchronization Input for RF Power Amplifier Pulse
    Events (TX)
  • Hardware Torch Enable (TORCH/TEMP)
  • Remote NTC Monitoring (TORCH/TEMP)
  • 400-kHz I2C-Compatible Interface
    • LM3643 (I2C Address = 0x63)
    • LM3643A (I2C Address = 0x67)
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The LM3643 is a dual LED flash driver that provides a high level of adjustability within a small solution size. The LM3643 utilizes a 2-MHz or 4-MHz fixed-frequency synchronous boost converter to provide power to the dual 1.5-A constant current LED sources. The total LED current the LM3643 boost can deliver is 1.5 A (ILED1 + ILED2 ). The dual 128 level current sources provide the flexibility to adjust the current ratios between LED1 and LED2 with each driver capable of delivering a maximum of 1.5 A (ex: ILED1 = 1.5 A and ILED2 = 0FF, ILED1 = 0FF and ILED2 = 1.5 A, or a current configuration with a current less than 1.5 A , ILED1 = 950 mA and ILED2 = 250 mA). An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.

Features of the LM3643 are controlled via an I2C-compatible interface. These features include: hardware flash and hardware torch pins (STROBE and TORCH/TEMP), a TX interrupt, and an NTC thermistor monitor. The device offers independently programmable currents in each output leg to drive the LEDs in a Flash or Movie Mode (Torch) condition.

The 2-MHz or 4-MHz switching frequency options, overvoltage protection (OVP), and adjustable current limit allow for the use of tiny, low-profile inductors and (10-µF) ceramic capacitors. The device operates over a –40°C to 85°C ambient temperature range.

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Technical documentation

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Type Title Date
* Data sheet LM3643 Synchronous Boost Dual LED Flash Driver with 1.5-A High-Side Current Sources datasheet (Rev. A) Nov. 17, 2014
White paper Common LED Functions and LED Driver Design Considerations Sep. 21, 2020
Application note LED Flash-Protection Features Aug. 23, 2017
Application note Using Flash LED Drivers for Infrared (IR) LED Applications Mar. 20, 2017
Application note Using the LM3643/4/8 in an Inductorless and/or Simplified PCB Routing Configurat Oct. 11, 2016
Technical article Here's how body electronics and lighting technology are changing the driving experience Sep. 26, 2016
Technical article LED brightness adjustment: high-frequency PWM dimming Aug. 26, 2016
Technical article Shrink your LED flash solution Dec. 10, 2015
Technical article Take better selfies with innovative LED flashes Nov. 18, 2014
User guide LM3643EVM User’s Guide Aug. 19, 2014

Design & development

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Hardware development

document-generic User guide

The LM3643EVM aids in evaluation of the LM3643 Synchronous Boost Dual LED Flash Driver W/ 1.5A High-Side Current Sources.  The 2/4 MHz synchronous boost provides up to 1.5A of total LED current to the dual independently controllable high side current sources.  Each current source can (...)

  • 1.5A of Total LED Current
  • Dual independently programmable current sources
  • 128 Brightness Levels per current source
  • I2C Control
  • External Enable, Strobe and Torch/Tx pins for control and synchronization

Software development

SNVC174.ZIP (2164 KB)

Design tools & simulation

SNVMA17.ZIP (77 KB) - PSpice Model
PSpice® for TI design and simulation tool
PSPICE-FOR-TI — PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
  • Leverages Cadence PSpice Technology
  • Preinstalled library with a suite of digital models to enable worst-case timing analysis
  • Dynamic updates ensure you have access to most current device models
  • Optimized for simulation speed without loss of accuracy
  • Supports simultaneous analysis of multiple products
  • (...)

CAD/CAE symbols

Package Pins Download
DSBGA (YFF) 12 View options

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